ah yes, didn't catch what you were saying in the original post...then yes, the redesigns should be accounted...but since they are only looking at E320s, the redesign hit should affect all years.
And in the case of the E-Class, 2009 was the last year of the old generation (W211 IIRC). So yes, if you graph E-Class prices right now, there will be a huge drop there.
If the 2010 Data Point is something he's purporting to be a "2010 E320" then it must not be a US model. In the US MY2010 began the W212 E-Class.
I applaud this guy for putting together so much data. I just wanted to raise this question because the way the data is presented confuses me a bit.